Method of treating ores by the blast-furnace process.



F. A. KJELLI'N. METHOD OF TREATING ORES BY THE BLAST FURNACE PROCESS.'APPLIUATLON FILED 0M. 23, 1909.

933,453; Patented Fm, 1911.";

1 1A [2' D Z) Q [kw/072 077 I m z fn'ssed await/n2 I UNITED sT trnsPATENT OFFICE.

' rn'nnmx. ADOLF KJELLIN, 0F srooxnomu, swnnnia.

METHOD TREATING ORES BY THE BLAST-FURNAGE PROCESS.;

Specification of Letters Patent.

Patented Feb. 7, 1911.

Application filed October 23, 1909. Serial No. 524,289.

To all wimn it my concern:

, Be it known that I, FREDRIK Anon KJELLIN, engineer, a subject of theKing of Sweden, residin atSturegata-n 56, Stockholm, Sweden, and usefulImprovements in Methods of Treating Ores by the Blast-Furnace Process,of which the following 'is'a specification.

In blast-furnaces of the design now in use experience, as is well known,has proved that the difi'erence of coal consumption per ton of iron forpoor and rich ores is considerably greater than is required for meltingthe greater or smaller quantity of gangue accompanying the ore. This011'- cumstance is, to a certain degree analogous with that occurringwhen hot blast is used,

which gives a greatersaving'of coal than that corresponding to theadditional heat quantity supplied by the heating of the blast. Thepeculiar circumstance, that the coal consumption in melting poor ores'isincreased-to a greater extent than the heat required for melting thegangue must depresence of a greater quan pend upon the tity of gangue 1nthe charge affecting the reduction process in the mi dle part of. the

furnace and especially in the part thereof,

where the reduction of the lower-oxidsof iron (probably Fe O to metalliciron begins. -This fact might be explained in the following way. If thereduction of the ore is supposed to take place gradually, so

that all the ore is reduced to Fe O, before metallic iron begins-toform, there is one cross-section of the furnace, immediately above whichthe ore is reduced to Fe O,,

-while immediately beneath the same partof Fe O is reduced to metalliciron. The

composition of the gases ascending through the furnace must thenat the.passage of the said section fulfil the following condition: Theproportion between their percentage of carbon monoxid and of carbondioxid must correspond to equilibrium between these gases'an'd carbon atthe temperature pre vailing in the section.

The ascending gases must have delivered, in the part of the furnacebelow the aforesaid section, the quantity of heat required for both thereduction of 'Fe O to Fe and for heating and melting of iron and gangue'lready heated to the temperature prevail ing in the said section.

The use of poor ores necessitates a greater ave invented certainnewquantity of heat in the part of the furnace below the aforesaidsection (where the reduction to metallic iron begins) and consequently agreater consumption of coke and b'lastper ton of iron. Theincre as'edamount of heat thereby produced in/tlfe lowest part of the furnacecauses an increased reduction of ore by means of solid carbon in themiddle part of the furnace and consequently a diminution of thereduction to metallic iron by means of carbon monoxid. As a' consequenceof this, the gases coming in contact- -with poor ores will have lessper-.

centage of carbon dioxid and higher temperature than with rich ores atthe section where the reduction to metallic iron begins.

The combustion of the coke thus becomes.

more imperfect, and the escaping gases have, as aforesaid, a highertemperature and constitute, moreover, a larger quantity for the samequantity of iron treated. Here lies the reason for the fact, that thecoke con.-

sumption per ton of iron in treating poor ores is greater than thatcorresponding to the fusionheatof the increased quantity of gangue inthe said poor ore.

The present invention has'for its object to overcome the above mentioneddefects and to make it possible to treat iron ores in the blast-furnaceunder more favorable conditions than hitherto. This is attained bysupplying, in an ordinary blast-driven furnace, by electrical heating anadditional amount of heat to the descending charge in that part of thefurnace, where the reduction of the lower oxids of iron to metallic ironbegins.

The electrical heating is preferably effected by conducting an electriccurrent through the charge at this point, whereby the current canbe ledthrough electrodes or con-. tact plates of carbon or of nnxturesof car-.

bon with magnesia, lime or other compounds conductive to the current ata high temtrated, provided with means for conducting an electric currentthrough the charge at that part of the furnace, where the reduction ofthe lower oxids of iron to metallic iron begins. In this drawing a isthe shaft,

7) the twy'ers for the blast and c, 0, two an- 7 nular electrodesconnected to a source of electricity in sucha manner that an electriccurrent passes between them through the charge, which thereby is heated.A quantity of heat corresponding to a heating of the charge a fewhundred degrees C. will thus he sufiicient; By such an additionalheating the influence of a. greater or smaller quantity of gangue' inthe ore upon the reactions in the furnace on account. of its speciticheat is thus eliminated, and in analogy quantity of heat by means ofelectricity in one or more sections of the furnace, but according to mypresent invention I contemplate electrically heating the descendingcharge in that section of a blast-furnace where the reduction of thelower oxids of iron to metallic iron begins, for the purpose alreadymentioned.

I claim The method of treating iron ores in blastfurnaces, whichconsists in feeding 'a charge of iron ore and fuel into a blast-furnace,heating the entire charge in the ordinary manner, and passin an electriccurrent through the charge in that section of the furnace where thereduction of the lower oxids of iron to metallic iron begins, for thefurther heating thereof.

in testimony whereof I have signed my 45 name to this specifimition inthe presence of two suhscrihing witnesses.

'FR-ICDRIK A none KJELLIN.

itnesses ll. 'lnnimonn, Brian-1a Nomirmin'r.

